This invention relates to a theftproof device, and more particularly to a flexible tying member forming part of a theftproof device and through which an optical fiber extends.
A theftproof device for vehicles such as motorcycles has been proposed by the assignee of the present application, which uses a flexible tying member such as a wire cable, through which an optical fiber extends. The proposed theftproof device is used in such a manner that a vehicle, which is to be protected from theft, is tied to a solid structure such as an electric pole, by means of the above flexible tying member, while a photo signal is permanently transmitted through the optical fiber. When the flexible tying member is cut in two to cause interruption of the transmission of the photo signal through the optical fiber, the cutting of the flexible tying member is detected in a photoelectric manner to actuate a warning device to give warning.
Such flexible tying member with an optical fiber incorporated therein should desirably have sufficient strength so as to withstand frequent use. Further, it should have a simple structure such that it can be manufactured at moderately low costs.